Various types of pulling apparatus have long been used in vehicle body and frame repair shops. Generally, both pulling apparatus falls into two categories: the more permanently installed frame rack-type straightening equipment and the lighter weight and portable post-type pulling devices which are moved around the body shop and anchored at various locations for making pulls in different directions. The more permanently installed frame rack or frame rail devices are much more expensive and are less versatile than the portable post-type straightening apparatus. It is the portable post-type pulling devices to which the present invention is directed.
Generally, post-type pulling apparatus comprises one or more vertically extending support members formed as a rigid post and having a guide such as a pulley attached to various elevations along the post. It is common to provide a plurality of vertically spaced apart holes in the post, and a shaft on which the pulley rotates can be inserted through the holes to vary the elevation of the pulley on the post. A pulling chain is led over the pulley and one end of the pulling chain is attached to a portion of a vehicle to which a pulling force is applied. The post also carries a tensioning device, generally a hydraulically-actuated piston arranged so that the other end of the pulling chain is connected to the hydraulic ram for exerting a pulling force on the portion of the vehicle to which the other end of the pulling chain is attached.
In use, the pulling apparatus rests on the floor of the body shop in a free-standing manner in the sense that the base of the post is not permanently or otherwise rigidly affixed to the floor, but simply rests on the floor. The post is anchored during a pull by an anchor chain extending from the post to at least one anchor pot embedded in the floor on a side of the post opposite from the side on which the pulling chain is attached to the vehicle. The anchor chain counteracts the pulling force exerted on the vehicle by the pulling chain.
Thus, the pulling apparatus is securely held in place by the counter-balancing forces as long as the anchor assembly remains firmly intact. However, if the anchor chain breaks or becomes detached from the floor anchor or the floor anchor otherwise lets loose during a pulling operation, the sudden release of the anchoring restraint may cause the pulling apparatus to move toward the vehicle in a violent manner. Such pulling apparatus is often subjected to rugged use or even occasional misuse, and routine inspection practices may not be adhered to by those using the equipment. The anchoring chain may become worn, fatigued or otherwise weakened, and inasmuch as there is often no convenient means for determining whether a link in the chain may be weakened, the chain may break under the stress of a pulling operation, and thereby allow the pulling apparatus to jump toward the vehicle with violence.
My U.S. Pat. No. 4,175,420 describes an approach to solving the problem of anchor chain failure, by providing attachment members on the post in combination with safety tie down anchoring lines attached at their free ends to floor anchors adjacent the pulling apparatus. The safety tie downs restrain or otherwise limit movement of the pulling post should a failure occur in the anchor assembly. In the safety tie down system disclosed in my patent, the safety tie down lines are preferably auxiliary cables or chains which extend from the sides of the post in a direction generally angularly outwardly away from the direction in which the pulling chain extends. The anchor lines thus extend generally toward the rear of the post, in the direction generally toward which the primary anchoring chain extends. Thus, if the anchor chain fails or the anchor pot becomes loose or pulls out of the floor, the safety tie down lines prevent the post from jumping forward.
Although the safety tie down apparatus disclosed in my '420 patent has proved to be an enormous success commercially, the present invention provides further improvements to the safety of post-type pulling apparatus. For instance, the safety tie down apparatus disclosed in my '420 patent requires that the safety tie down lines be connected to auxiliary anchor pots located to the rear and spaced laterally outwardly from both sides of the post, so that the safety tie down lines extend to the rear of the post in an outwardly diverging pattern. This requires that the floor of the repair shop have an array of anchor pots available so that the safety tie down lines can be fastened to two additional anchor pots, over and above the anchor pot or pots to which the primary anchor chain is attached. This requires repairmen to take the additional time to connect the safety tie down lines to both anchor pots each time a pull is to be made. Because of the additional setup time required to properly restrain the post, many repairmen disregard safety and use the post without attaching the safety tie down lines. Moreover, if the pulling post is located in any one of the four corner regions of the anchor pot array on the floor, then there may not be anchor pots available at the necessary locations on the floor for attachment of both safety tie down lines, even if the repairman wants to attach the safety tie down lines.
Therefore, there is a need to provide a safety tie down system for the free-standing type of pulling post which simplifies the steps necessary to safely hook up the post with each repositioning of the post. The safety tie down arrangement also should be capable of use in any region of a floor array of anchor pots, including any of the corner regions. In this way, the repairman will be able to readily use the safety tie down arrangement for applying pulls in all directions; and as a result, the repairman will be more encouraged to use the safety tie down system when each and every pulling force is applied.